Fully Submerged Composite Cryogenic Testing

1 General Introduction New methods for marine salvage and decommissioning of structures in the open sea are continually being sought in order to improve control and lower operational costs [1]. The concept design of a lightweight, cryogenic, marine, heavy lift, buoyancy system has been investigated [2]. The objective is to be able to raise or lower high mass objects controlled solely from a surface support vessel. The overall design concept and associated system development issues have been discussed previously. A number of the sub-systems in one complete buoyancy system involve considerable design and development, these include: structural design of the buoyancy chamber, mechanical systems to control and connection to the lift device, the cryogenic system itself and overall process control systems. The main area of concern in the design process is the composite cryogenic Dewar. This is required to operate not only at temperatures as low as -196 o C but also to withstand pressure differences exceeding 35bar. As such the composite materials have to perform in a very aggressive environment. This work details a method for fully submersed composite cryogenic testing in order to qualify the materials for use in the Dewar of the buoyancy system.